The present invention relates to a thoracentesis device which is used in the removal of fluid from the pleural cavity, and more particularly to a thoracentesis device of this type which prevents air entry into the pleural cavity and lung puncture during its use.
In performing thoracentesis, an incision is made through the chest wall and a tube or catheter inserted through the incision into the pleural cavity. The proximate end of the catheter is connected to a negative pressure source e.g., a pump, and intrathorasic fluid, blood, air, or other secretions are then removed from the pleural cavity through the catheter.
Removal of fluid or other materials from the pleural cavity presents problems which are unique to this body cavity. In order for the lungs to remain expanded, there must be a negative pressure within the pleural cavity. Any communication between the pleural cavity and atmospheric pressure can result in a sudden rush of air from outside the body into the pleural cavity. This can produce a collapsed lung and a medical condition known as pneumothorax. Thus, it is important to insure that the pleural cavity is at all times sealed from atmospheric air.
A common method of making the chest wall incision in this procedure is to use a needle. However, if a needle is introduced into the pleural cavity too far, it can puncture the surface of the lung. In this case, air from the lung air spaces (alveoli) or from the air passages (bronchi) can escape into the pleural cavity and can produce a lung collapse (pneumothorax). This is a dangerous condition because air can continue to escape from the lung and produce a pressure within the pleural cavity which is actually greater than atmospheric pressure. This condition is known as tension pneumothorax and can produce serious interference with cardiac function and possible death.